Releasable corrosion inhibitors

ABSTRACT

The present invention includes compositions and methods of supplying a corrosion inhibitor including placing a corrosion inhibitor attached to a nanostructure carrier, placing the nanostructure carrier containing the corrosion inhibitor at a location and the nanostructure carrier is capable of releasing the corrosion inhibitor.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

FIELD

Embodiments of the present invention relate to corrosion inhibitors foruse in a corrosive environment. Embodiments of the present inventionrelate generally to materials and methods of their use that release oneor more types of corrosion inhibitors upon command or in a predeterminedmanner.

BACKGROUND

Oilfield operations typically involve the use of mechanical equipment,such as pumps and motors. This equipment is generally made of metallicsubstances and requires maintenance to continue to function properly. Inthe course of oil and gas drilling and production, this mechanicalequipment may be present in downhole and subsea environments. Theseenvironments typically are corrosive environments. Such corrosiveenvironments contribute to the corrosion of the mechanical equipment,including motors and pumps, which can cause them to fail.

Corrosion can cause problems in oilfield operations. Corrosion canincrease drilling and production costs. Corrosion can also causedowntime in drilling, which leads to increased costs. To overcome thesecosts and delays, mechanical equipment having a hardened coating, suchas a tungsten carbide coating, has been used to provide enhancedcorrosion and wear resistance. However, due to the elevated costs ofthese coatings, only a small percentage of mechanical equipment in thefield has this coating.

Corrosion inhibitors have been used to contain or prevent corrosion.Certain corrosion inhibitors include surfactants, which have beenemployed to inhibit corrosion or to improve the performance of certainorganic corrosion inhibitor systems. Many oil wells produce mixtureshaving high water content, therefore, conventional oil-soluble mixtureshave been formulated with both fatty acids and a variety of surfactants.

However, this approach has proven limited in its scope. The use ofenough surfactant to render the oil-soluble molecule water-soluble hasdramatically reduced film formation and film persistency, leaving thecorrosion inhibitor susceptible to washing off of the metal, leaving themetal unprotected. Also, these inhibitors have a tendency to emulsifyunder downhole conditions, resulting in major problems for the user.Although these inhibitors have found limited use in oil and gaspipelines, they have not yet proven to successfully inhibit corrosionwhen utilized under the environments typical of producing oil wells.

In addition, corrosion in an oilfield environment may be initiated at aspecific location on a specific piece of equipment at a specific time.However, such information on where and when corrosion may start may notbe available to technicians in the oil field. This delay allows for thecorrosion to progress, resulting in greater damage to mechanicalequipment in the field.

In view of the above, it would be desirable to have an improved deliverysystem that supplies a sufficient amount of corrosion inhibitor atspecific locations in order to stop or contain the corrosion in itsearly stages. It would also be desirable to supply a corrosion inhibitorthat would be successful in containing or preventing corrosion under theenvironments typical of producing oil wells.

SUMMARY

In an embodiment, a method of supplying a corrosion inhibitor to a metalcomprises combining a corrosion inhibitor with a nanostructure carrier(the combination referred to herein as “a corrosioninhibitor/nanostructure carrier combination”). As used herein, the term“combine” or “combining” refers to the incorporation of two or moreentities via any suitable interaction known to one skilled in the art.Such interaction includes and is not limited to adsorption(chemisorption and physisorption), chemical bonding, and electrostaticinteraction.

In another embodiment, a method of supplying a corrosion inhibitor to ametal comprises placing a corrosion inhibitor/nanostructure carriercombination in the vicinity of a metal where it is capable of releasinga corrosion inhibitor. In some embodiments, the method further comprisesattaching a corrosion inhibitor to a nanostructure carrier to form thecorrosion inhibitor/nanostructure carrier combination. In someembodiments, the method further comprises releasing the corrosioninhibitor from the corrosion inhibitor/nanostructure carriercombination.

In a further embodiment, the corrosion inhibitor/nanostructure carriercombination is combined with a lubricant, an elastomer, a coating,placed within the matrix of a metallic surface, located within a solidencapsulated bearing, or combinations thereof.

In an embodiment, the corrosion inhibitor is released upon normal wearof the metallic surface, under standard operating conditions, and/orupon a triggering condition. In another embodiment, the corrosioninhibitor is released over time or upon a change in condition such asupon a change in pressure, temperature, or pH.

In yet a further embodiment, the corrosion inhibitor is located adjacentto an oilfield tool such as a drill bit, a rotor, a stator, a motor, apump, a drive shaft assembly, a dump sub, a bearing assembly, a blowoutpreventer (BOP), a packer, drill pipe, tubing, casing, a completiontool, a production tool, a fishing tool, an agitator, a stabilizer, acentralizer, and combinations thereof.

In an embodiment, the corrosion inhibitor is located within one or moreelastomeric component, referred to as an elastomer. In some embodiments,the elastomer is permeable to the corrosion inhibitor and capable ofreleasing the corrosion inhibitor from the elastomer under standardoperating conditions. In some embodiments, the elastomer isnon-permeable to the corrosion inhibitor under standard operatingconditions and permeable to the corrosion inhibitor under imposedconditions. In some cases, the elastomer is permeable to the corrosioninhibitor under a change in pressure, a change in temperature, a changein pH, or is increasingly permeable to the corrosion inhibitor overtime.

Also disclosed herein is a composition for inhibiting corrosion,comprising a nanostructure carrier with a corrosion inhibitor attachedforming a corrosion inhibitor/nanostructure carrier combination. In someembodiments, the corrosion inhibitor/nanostructure carrier combinationis selected from the group consisting of graphines, nanotubes,nanohorns, nanolattice, and combinations thereof. In some embodiments,the corrosion inhibitor/nanostructure carrier combination is locatedadjacent to an oilfield tool, such as a drill bit, a rotor, a stator, amotor, a pump, a drive shaft assembly, a dump sub, a bearing assembly, ablowout preventer, a packer, drill pipe, tubing, casing, a completiontool, a production tool, a fishing tool, an agitator, a stabilizer, acentralizer, and combinations thereof.

In an embodiment, a method of preventing corrosion comprises combining acorrosion inhibitor with a nanostructure carrier, containing thecorrosion inhibitor and nanostructure carrier within an elastomer, andplacing the elastomer containing the corrosion inhibitor in the vicinityof a surface subject to corrosion wherein the elastomer is permeable tothe corrosion inhibitor and capable of releasing the corrosion inhibitorfrom the elastomer. In some embodiments, the elastomer is locatedadjacent to an oilfield tool, such as a drill bit, a rotor, a stator, amotor, a pump, a drive shaft assembly, a dump sub, a bearing assembly, ablowout preventer, a packer, drill pipe, tubing, casing, a completiontool, a production tool, a fishing tool, an agitator, a stabilizer, acentralizer, and combinations thereof.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an illustration of a PC pump in accordance with an embodiment,of the present invention.

FIG. 2 is a cross sectional illustration of a rotor and stator of a PCpump in accordance with an embodiment, of the present invention.

FIG. 3 is a cross sectional illustration of a bottom hole assembly withcomponents incorporating an embodiment, of the present invention.

FIG. 4 is a cross sectional illustration of bottom hole assembly with abearing assembly in accordance with an embodiment, of the presentinvention.

FIG. 5 is an illustration of a roller cone drill bit having elements inaccordance with an embodiment, of the present invention.

FIG. 6 is a cross section of a roller cone drill bit illustrating abearing assembly having elements in accordance with an embodiment, ofthe present invention.

FIG. 7 is an illustration of a fixed cutter drill bit having elements inaccordance with an embodiment, of the present invention.

FIG. 8 is an illustration of a drill string stabilizer having elementsin accordance with an embodiment, of the present invention.

FIG. 9 is an illustration of a variable gauge stabilizer having elementsin accordance with an embodiment, of the present invention.

FIG. 10 is an illustration of a centralizer having elements inaccordance with an embodiment, of the present invention.

FIG. 11 is an illustration of an agitator having elements in accordancewith an embodiment, of the present invention.

FIG. 12 is an illustration of a packer having elements in accordancewith an embodiment, of the present invention.

FIG. 13 is an illustration of a fishing tool having elements inaccordance with an embodiment, of the present invention.

FIG. 14 is an illustration of a blow out preventer having elements inaccordance with the present invention.

FIG. 15 is an illustration of a blow out preventer having elements inaccordance with an embodiment, of the present invention.

DETAILED DESCRIPTION

The present invention includes methods and compositions directed tolocalized and generalized on demand release of and distribution ofcorrosion inhibitors.

Corrosion inhibitors can be generally divided into two broad categories,those that enhance the formation of a native protective oxide filmthrough an oxidizing effect, and those that inhibit corrosion byselectively adsorbing on the metal surface and creating a barrier thatprevents access of the corrosive agent to the surface. In the formergroup are materials such as inorganic chromates, inorganic nitrates,molybdates and organic nitrates. The latter group includes materialssuch as carbonates, silicates and phosphates and organic moleculescontaining heteroatoms such as nitrogen, sulfur, phosphorus and oxygen(e.g. materials such as anthranilic acid, thiols, organic phosphonatesand organic carboxylates). Some of these materials also act as poisonsfor the cathodic oxygen reduction reaction that is linked to the anodicdissolution of the metal. Slowing down the cathodic reaction slows downthe overall corrosion reaction.

In various embodiments, any corrosion inhibitor as described above, orany combination of two or more corrosion inhibitors may be used toprovide sufficient inhibition of corrosion of metallic surfaces. In somecases, the metallic surfaces include surfaces made of metals or alloys.In an embodiment, the corrosion inhibitor is effective for surfaces madeof a metal or alloy selected from the group consisting of aluminum,steel, stainless steel, brass, bronze, carbon steel, copper, ferrousmaterials, iron, magnesium, nickel, titanium, and zinc. In anotherembodiment, the corrosion inhibitor is effective for surfaces made of amaterial selected from the group consisting of aluminum, aluminumalloys, stainless steel, carbon steel, and cast iron. In a furtherembodiment, the corrosion inhibitor is effective for surfaces made of amaterial selected from the group consisting of alloy steels, stainlesssteel, carbon steel, cast iron, and ferrous materials.

From a different perspective, corrosion inhibitors can be classifiedinto the following classifications: passivating inhibitors, cathodicinhibitors, organic inhibitors, precipitation inhibitors, and volatilecorrosion inhibitors. In an embodiment, the corrosion inhibitor isselected from the group consisting of soluble chromates, cerates,molybdates, and vanadates. In an embodiment, the corrosion inhibitor isan organic corrosion inhibitor selected from the group consisting ofweak acids, carboxylates, and amine thiols. In an embodiment, thecorrosion inhibitor is a combination of organic anions and cations thatoffers enhanced corrosion protection.

In a further embodiment, a nanostructure carrier is used to supply thecorrosion inhibitor to a desired location in the oilfield. In variousembodiments, the carrier have the ability to hold the corrosioninhibitors in a non-leachable or slowly-leachable form until the onsetof metal corrosion triggers the release of the corrosion inhibitor, orat such time as the corrosion inhibitor is released through a triggeringmechanism, such as a change in condition (e.g., temperature orpressure). In embodiments, the use of a nanostructure carrier increasesthe longevity of the corrosion inhibitors (or the duration of theeffectiveness of the corrosion inhibitors). In embodiments, anynanostructure carrier may be used, wherein the nanostructure carrier iscapable of holding or containing a corrosion inhibitor in anon-leachable or slowly-leachable fashion until a triggering mechanismis activated.

In an embodiment, the nanostructure carrier used to supply the corrosioninhibitor is added to a carrier, such as grease. In some embodiments,such carriers comprise oils, lubricants, hydraulic fluids, drillingfluids, completion fluids, or the like. In an embodiment, the corrosioninhibitor/nanostructure carrier combination is mixed with the greasebefore the grease is added to a corrosion susceptible location on aselected piece of mechanical equipment. In various embodiments, thegrease with the combination contained therein is added to locations suchas the grease seals within a pump as well as all of the metal surfacesof the mechanical equipment that are susceptible to corrosion. In anembodiment, at least a majority of the grease joints in a piece ofmechanical equipment contain the corrosion inhibitor/nanostructurecarrier combination containing grease. In another embodiment, all of thegrease joints in a piece of mechanical equipment contain the corrosioninhibitor/nanostructure carrier combination containing grease. In anembodiment, at least a majority of the grease seals in a piece ofmechanical equipment contain the corrosion inhibitor/nanostructurecarrier combination containing grease. In another embodiment, all of thegrease seals in a piece of mechanical equipment contain the corrosioninhibitor/nanostructure carrier combination containing grease. In somecases, the corrosion inhibitor containing grease does not contain claynanoparticles. In this disclosure, any type of grease common for usewith metallic surfaces may be used. In an embodiment, the grease isselected from the group consisting of mineral oil(s) mixed with solids,heavy asphaltic oil mixed with lighter mineral oil, extreme pressuregrease, roll neck grease, and soap thickened mineral oils includingsodium-base, barium-soap, lithium-soap, or calcium-soap, andcombinations thereof.

In an embodiment, the nanostructure carrier used to supply the corrosioninhibitor is a nanocomposite or a material having nanoporosity. In someembodiments, nanocomposites include nanoparticles such as layeredsilicates, including clays. In an aspect, the nanocomposites have atleast one phase having at least one dimension in the range of 0.1 to 100nm. In another aspect, the nanocomposites have at least one phase havingat least one dimension in the range of 20 to 70 nm. In an embodiment,the nanostructure carrier is a carbon based material such as carbonblack, carbon nanotube, carbon nanohorn, carbon nanobud, and the like.In an embodiment, the nanostructure carrier is a fullerene. As usedherein, nanoparticles are materials having three dimensions on thenanoscale; and nanotubes or the like are materials having two dimensionson the nanoscale. As used herein, the term “nanostructure” refers to amaterial having at least one phase having at least one dimension in therange of 0.1 to 100 nm.

In a further embodiment, the nanostructure includes polymer compositionsor components. In various embodiments, such polymers include anypolymeric component or combinations of polymeric components that arecapable of forming polymer nanoparticles or having nanoporosity. In anembodiment, the polymers utilized in the nanoparticles or particleshaving nanoporosity include polyamide, polyacetal, polycarbonate,polyoxytetramethyleneoxyterephthaloyl, polybutyleneterephthalate,polyethyleneterephthalate, polyimide, polyphenylenesulfide, polysulfone,polyarylate, epoxy, or polyphenylene ether resins. In some embodiments,the polymers are mixed with 0.05 to 30 weight percent of a layeredsilicate. In some other embodiments, the polymers are mixed with 1 to 10weight percent of a layered silicate. In some further embodiments, thepolymers are mixed with 3 to 7 weight percent of a layered silicate.Such weight percentages are on the basis of the total weight of thepolymer-silicate mixture. In various embodiments, the polymers are dryblended with the layered silicate in a suitable mechanical mixer knownto one skilled in the art.

In embodiments, layered silicates include materials such as clays. In anaspect, the layered silicates include 1:1 type layered silicatesstructured by one tetrahedral layer per one octahedral layer. In anotheraspect, the layered silicates include 2:1 type layered silicatesstructured by two tetrahedral layers per one octahedral layer. In someembodiments, the 1:1 type layered silicate includes kaolinite,halloysite, chrysotile, or the like. In some embodiments, the 2:1 typelayered silicate includes a smectite mineral such as montmorillonite,hectorite, beidellite, and saponite; a mica mineral such as muscoviteand phlogopite; talc; pyrophyllite; vermiculite; and chlorite.

Clay generally describes crystalline, plate-like, 2-dimensional layeredlattice alumino silicates. Thus, for example, clays of the smectite,halloysite, illite, kaolinite, montmorillonite, palygorskite groups, andvarious other similar materials are herein referred to as clays. As usedherein, the term “clays” also refer to nanoclays or clay nanotubes,nanohorns, and the like. In some embodiments, clays are utilized as acarrier to supply the corrosion inhibitor. In various embodiments, thecorrosion inhibitor is attached to the clays, encapsulated within theclay structure, or contained within the pores or nanopores of the clayor clay based composition. In an embodiment, the carrier is boehmite ora boehmite based composition.

In an embodiment, the layered silicate is a metal oxyhydroxide. In afurther embodiment, the metal oxyhydroxide is selected from the groupconsisting of iron, aluminum, copper, magnesium, chromium, zinc andtitanium. In some cases, the metal oxyhydroxide is treated withchemicals to modify the surface of the nanoparticles and to reduce theparticle size down to ranges of from 20 to 70 nm. In some cases, thechemical treatment anchors the organic corrosion inhibitors to theoutside surface of the nanoparticles. In some other cases, the chemicaltreatment changes the surface to create nanopores. In embodiments, thecorrosion inhibitor is located within the nanoparticle structure,between nanoparticles, within the nanopores of the carrier, orcombinations thereof.

In an embodiment, the metal oxyhydroxide is an aluminum metal hydroxide.In some cases, such aluminum metal hydroxide, also referred to asboehmite (AlOOH), comprises those produced by Sasol North America as aby-product in the production of surfactants. In some cases, theseboehmite particles are surface modified with carboxylic acids, such asacrylic acid. In some embodiments, these surface modified boehmiteparticles serve as on-demand releasable carriers for corrosioninhibitors if the inhibitor is bound to the boehmite surface through apH cleavable carboxylate bond. In embodiments, the initial chemicalmodification of the boehmite takes place by heating functionalizedcarboxylic acids in the presence of water and boehmite. For instance,acrylic acid contains an activated double bond. Once the acrylic acidactivates the boehmite nanoparticle surface, the surface modifiednanoparticles are heated in water with a corrosion inhibitor, resultingin corrosion inhibitors being anchored to the nanoparticles creatingcorrosion inhibitor containing carriers.

Boehmite and pseudoboehmite are aluminum oxyhydroxides of the generalformula γ-AlO(OH).xH₂O. When x=0 the material is called boehmite; whenx>0 and the materials incorporate water into their crystalline structurethey are known as pseudoboehmite. Boehmite and pseudoboehmite are alsodescribed as Al₂O₃.zH₂O where, when z=1 the material is boehmite andwhen 1<z<2 the material is pseudoboehmite. For the purposes of thisspecification, the term “boehmite” implies boehmite and/orpseudoboehmite.

Aluminum oxyhydroxide is to be broadly construed to include any materialwhose surface is or may be processed to form a shell or layer ofboehmite, including specifically aluminum metal, aluminum nitride,aluminum oxynitride (AlON), α-Al₂O₃, γ-Al₂O₃, transitional aluminas ofgeneral formula Al₂O₃, boehmite (γ-AlO(OH)), pseudoboehmite(γ-AlO(OH).xH₂O where 0<x<1), diaspore (α-AlO(OH)), and the aluminumhydroxides (Al(OH)₃) of bayerite and gibbsite.

Iron oxyhydroxide is also known as lepidocrocite, γ-FeO(OH). Boehmiteand pseudoboehmite have a crystal structure that is isomorphous withlepidocrocite. Solid solutions of iron oxyhydroxide and boehmite arealso known and may be referred to as either material when there is not agreat predominance of one metal or the other.

In an embodiment, corrosion inhibitors are anchored to a nanostructurecarrier material, such as boehmite and pseudoboehmite, throughmodification of the surface of the carrier material. In one embodiment,a corrosion inhibitor is anchored to the carrier material with acarboxylic acid. Methods of modifying the surface of particles aredisclosed in U.S. Pat. Nos. 6,887,517; 6,933,046; 6,986,943; and7,244,498 to Cook et al., the disclosures of which are incorporated byreference herein in their entirety.

In various embodiments, the treated materials exhibit benefits for useas carriers for corrosion inhibitors. One advantage in utilizing treatednanostructures, or materials having nanopores, as carriers is that thecorrosion inhibitors are non-leachable or leachable at low rates fromthe treated carriers, greatly reducing the rate at which the corrosioninhibitors are released. Another advantage is that the release of theinhibitors is on demand, such as by utilizing a triggering mechanism.

In embodiments, various triggering mechanisms include: pH, solubility,pressure, temperature, chemical, mechanical, and time-based triggers. Insome cases, mechanical triggers include impact, surface agitation,abrasion, shear, and any other means that causes an alteration to astructure to facilitate the release of corrosion inhibitor. In othercases, triggering mechanisms include a combination of mechanisms, suchas a mechanical act that initiates a chemical or pH change. For example,a mechanical trigger releases a chemical agent that in turn activatesthe release of the corrosion inhibitor. All suitable triggeringmechanisms are considered to be within the scope of the presentinvention.

Certain types of corrosion cause a rise in pH in regions affected by thecorrosion. In such situations, the organic corrosion inhibitors aretethered to the surface of the treated nanostructures through a bondthat is broken at a high pH, thereby providing a pH dependent releasemechanism. In some embodiments, the corrosion inhibitor is releasedwhen/and where it is needed, resulting in more efficient use of thecorrosion inhibitors.

Certain properties of the nanostructure carrier allow for the use of ahigh concentration of corrosion inhibitors. One advantage in usingnanostructures or materials having nanopores as carriers is that theyhave a high surface area. This high surface area creates the capacity tostore a large amount of corrosion inhibitors, allowing for a highconcentration of corrosion inhibitors to be used. The use of a highconcentration of corrosion inhibitors extends the lifetime of thecorrosion releasing nanostructure carrier, which provides improvedprotection of the coated metals. The on-demand release characteristic ofthe treated nanostructure carrier allows for the use of a highconcentration of corrosion inhibitors. A benefit of having a highconcentration of on-demand corrosion inhibitors is that the presence ofcorrosion is treated with a high dose of corrosion inhibitors when thetriggering signs of corrosion are present, such as a high pH. Thesesurface-modified carriers are useful when used in mixtures with liquidsor when used as fillers in solids.

In embodiments, the corrosion inhibitor containing compositions of thepresent invention are applicable to any type of metallic surface that issusceptible to corrosion. In an embodiment, the metallic surfacesinclude mechanical equipment that is susceptible to corrosion. Inanother embodiment, the corrosion inhibitor containing compositions areapplicable to any type of mechanical equipment commonly used in oilfield applications. In a further embodiment, the mechanical equipmentincludes equipment selected from the group consisting of a drill bit, arotor, a stator, a motor, a pump, a drive shaft assembly, a dump sub, abearing assembly, a blowout preventer (BOP), a packer, drill pipe,tubing, casing, a completion tool, a production tool, a fishing tool, anagitator, a stabilizer, a centralizer, and combinations thereof. In aspecific embodiment, the corrosion inhibitor containing compositions areapplicable to a steel rotor and a stator of a pump.

In an embodiment, the corrosion inhibitor containing nanostructurecarrier is included within an elastomer at a desired location within apiece of mechanical equipment. In an embodiment, the corrosion inhibitorcontaining nanostructure carrier is dispersed throughout the matrix ofan elastomer. In an embodiment, the corrosion inhibitor containingnanostructure carrier is dispersed throughout the matrix of a statorelastomer and is released on demand during use. In an embodiment, thecorrosion inhibitor containing nanostructure carrier is dispersedthroughout the matrix of the elastomers of a roller cone drill bit sealand may be released on demand during use. In an embodiment, thecorrosion inhibitor containing nanostructure carrier is dispersedthroughout the matrix of an elastomer placed in a blowout preventer(BOP) wherein the corrosion inhibitor is released on demand. In anembodiment, the corrosion inhibitor containing nanostructure carrier isdispersed throughout the matrix of an elastomer placed in a packerwherein the corrosion inhibitor is released on demand.

In an embodiment, the corrosion inhibitor nanostructure carrier, such asa layered silicate, is contained within an elastomer at a desiredlocation within or attached to a piece of mechanical equipment. In somecases, the elastomer contains the nanostructure carrier and corrosioninhibitor. In some cases, the elastomer is non-permeable to thenanostructure carrier while being permeable to the corrosion inhibitor,thereby enabling the corrosion inhibitor to be released through theelastomer at a known rate or under certain imposed conditions. In oneembodiment, the elastomer is permeable to the corrosion inhibitor withina known range of conditions. For example, the elastomer is permeable tothe corrosion inhibitor at a known rate under normal operatingconditions, such that the corrosion inhibitor is released at asubstantially constant rate while in operation. In an alternativeembodiment, the elastomer is permeable to the corrosion inhibitor underabnormal operating conditions, such that the corrosion inhibitor isreleased upon the imposition of a condition change, such as an imposedpressure elevation or increase.

In an embodiment, the corrosion inhibitor containing nanostructurecarrier is included within a coating on at least a portion of themechanical equipment. In an embodiment, the coating includes a sealant,a tungsten carbide coating, a chrome sealant, or an epoxy. The coatingmay be used in any desired location on the mechanical equipment. In afurther embodiment, the coating having a corrosion inhibitor containingnanostructure carrier is applied to the area(s) of the mechanicalequipment that are susceptible to corrosion.

In an aspect, a power section rotor has a protective coating on theouter surface, wherein the coating contains a corrosion inhibitingadditive in which organic corrosion inhibitors are anchored tonanostructures having high surface areas. The corrosion inhibitors arereleased on-demand or upon a triggering event. In some embodiments, thecorrosion inhibitors are applied on the outer surface as a part of aresin from which they are released when corrosion occurs. In some otherembodiments, the corrosion inhibitors are placed in a reservoir or acapsule situated in a rotor cavity or attached to the rotor outerdiameter from which they are released on-demand to stop or retardcorrosion.

In certain embodiments, the release of corrosion inhibitors is under thecontrol of workers in the field. In an embodiment, the release ofcorrosion inhibitors is brought about by an increase in pressure, whichis controlled by workers in the field. The increase in pressure isapplied to the carrier, causing the release of the corrosion inhibitor.

In an embodiment, the corrosion inhibitor is included within the matrixof a piece of mechanical equipment. In some cases, the corrosioninhibitor is included within the matrix of a portion of a drill bit andthe corrosion inhibitor is released upon the wearing down of the portioncontaining the inhibitor. In an embodiment, the corrosion inhibitor isdispersed throughout the matrix of a portion of a piece of mechanicalequipment such as a cladding on the surface. As the cladding is eroded,the corrosion inhibitor is released. In some other embodiments, thecorrosion inhibitor is included in the matrix of an addition to thepiece of mechanical equipment in an area that is known to experienceerosion. For example, the corrosion inhibitor is included within thematrix of an insert that is placed within a zone of high erosion, suchas where a significant flow of solid laden fluid is located. Upon thenatural erosion of the insert from the fluid flow, the corrosioninhibitor contained within the matrix of the insert is released.

FIG. 1 is a cross sectional illustration of a progressive cavity (PC)pump in accordance with an embodiment of the invention. The PC pump 10includes a rotor 12 and a stator 14 contained within a housing 16. In anembodiment, the corrosion inhibitor is incorporated within the matrix ofthe rotor 12, the stator 14, the housing 16, or other portion of the PCpump 10. In an embodiment, the corrosion inhibitor is incorporatedwithin a coating of the rotor 12, the stator 14, the housing 16, orother portion of the PC pump 10 such as bearings or seals (not shown).In an embodiment, the corrosion inhibitor is incorporated within theelastomer portions of the stator 14.

FIG. 2 is a cross sectional illustration of a rotor and stator of a PCpump in accordance with an embodiment of the invention. The PC pump 10includes a rotor 12 and a stator 14 contained within a housing 16. In anembodiment, the corrosion inhibitor is incorporated within the matrix ofthe rotor 12, the stator 14, the housing 16, or other portion of the PCpump 10. In an embodiment, the corrosion inhibitor is incorporatedwithin a coating of the rotor 12, the stator 14, the housing 16, orother portion of the PC pump 10 such as bearings or seals (not shown).In an embodiment, the corrosion inhibitor is incorporated within theelastomer portions of the stator 14. In an embodiment, the corrosioninhibitor is incorporated in a PC pump 10 used to create torque for adownhole tool or drill bit or in a PC pump 10 used as a lift pump toraise production fluids from the well.

FIG. 3 is an illustration of a bottom hole assembly (BHA) 19 havingcomponents in accordance with an embodiment of the invention. The BHAincludes a mud motor portion 20 with drive components 21, a drive shaftassembly 22 with a universal joint 23, a stabilizer 24, and a drill bit25. In an embodiment, the corrosion inhibitor is incorporated within thematrix of the motor components 21 such as a rotor and stator asdescribed above with the PC pump 10 in FIGS. 1 and 2. In an embodiment,the corrosion inhibitor is incorporated within any components of thedrive shaft assembly 22 or the universal joint 23, including anyelastomeric portions or seals incorporated therein. In a furtherembodiment, the corrosion inhibitor is incorporated within the matrix ofthe stabilizer 24 or the drill bit 25. In an embodiment, the BHA 19 issuspended from drill pipe or coiled tubing.

FIG. 4 is an illustration of a BHA 26 having a bearing assembly 27 inaccordance with an embodiment of the invention. The bearing assembly 27contains bearings 28, seals (not shown), and a passage to permitdrilling mud to pass through to a drill bit 29. In an embodiment, thecorrosion inhibitor is incorporated within the matrix of the bearingassembly 27 and within the bearings. In an embodiment, the corrosioninhibitor is incorporated within wear surfaces within the bearingassembly 27 to enable release of the corrosion inhibitor. In anembodiment, the seals within the bearing assembly are elastomeric. In anembodiment, the corrosion inhibitor and/or nanostructure carrier isincorporated within the elastomeric seals.

FIG. 5 is an illustration of a drill bit 30 having elements inaccordance with an embodiment of the invention. The bit has an externalsurface 32, one or more cutting elements 34, one or more nozzles 36, maycontain recessed areas 38, and may contain bearings 40. In anembodiment, the corrosion inhibitor is incorporated within the matrix ofthe bit. In an embodiment, the corrosion inhibitor is contained withinthe matrix of a coating on a portion of the surface 32, such as ahardfacing material. In an embodiment, the corrosion inhibitor isincorporated within the matrix of the nozzle 36 or adjacent to thenozzle 36 such that flow of drilling fluid through the nozzle 36 enablesthe release of the corrosion inhibitor, such as through a known erosionrate of the nozzle or an attachment thereof. In an embodiment, thecorrosion inhibitor is incorporated within the matrix of a bearing 40 orseal. In an embodiment, the corrosion inhibitor is incorporated withinan insert, such as placed within a recessed area 38 of the bit.

In an embodiment, the corrosion inhibitor is incorporated within thematrix of any bearing assembly for use in a corrosive environment. Byway of a non-limiting example, FIG. 6 illustrates the cross section of aroller cone drill bit having elements in accordance with an embodimentof the invention. Bearing assemblies of motors, pumps, and blow-outpreventers, and drill string tools may also have elements in accordancewith an embodiment of the invention as similarly illustrated in FIG. 6.In an embodiment, the corrosion inhibitor and/or nanostructure carrieris incorporated within an elastomeric seal 42. In an embodiment, thecorrosion inhibitor is incorporated in a lubricant stored in a reservoir44 for lubricating bearings 46. In a further embodiment, the corrosioninhibitor is incorporated within the bearing spindle 48 or another wearsurface within the bearing assembly to enable release of the corrosioninhibitor.

FIG. 7 is an illustration of a fixed cutter drill bit 70 having elementsin accordance with an embodiment of the present invention. The bit hasan external surface 72, one or more cutting elements 74 on one or moreblades 75, one or more nozzles 76, may contain recessed areas 78, andmay contain abrasive resistant inserts 79. In an embodiment, thecorrosion inhibitor is incorporated within the matrix of the bit and iscontained with the matrix of a coating on a portion of the surface 72such as hardfacing material. In an embodiment, the corrosion inhibitoris incorporated within the matrix of the nozzle 76 or adjacent to thenozzle such that flow of drilling fluid through the nozzle 76 enablesthe release of the corrosion inhibitor, such as through a known erosionrate of the nozzle or an attachment thereof. In a further embodiment,the corrosion inhibitor is incorporated within the matrix of the blades75 such that erosion of the blades 75 enables the release of thecorrosion inhibitor. In an embodiment, the corrosion inhibitor isincorporated within a cutting element 74 or an insert 79 that is placedwithin a recessed area 78.

FIG. 8 is an illustration of a drill string stabilizer having elementsin accordance with an embodiment of the present invention. Thestabilizer has an external surface 80, one or more blades 81, and one ormore recessed areas 82. In an embodiment, the corrosion inhibitor isincorporated within the matrix of the stabilizer, and is containedwithin the matrix of a coating on a portion of the surface 80 such ashardfacing material. In another embodiment, the corrosion inhibitor isincorporated within a blade 81 or a recessed area 82 such that erosionof the blade 81 or the recessed area 82 enables the release of thecorrosion inhibitor.

FIG. 9 is an illustration of a variable gauge stabilizer having elementsin accordance with an embodiment of the present invention. The variablegauge stabilizer has an external surface 90, one or more blades 91, oneor more recessed areas 92, and a plurality of actuated pistons 93. In anembodiment, like the stabilizer of FIG. 8, the corrosion inhibitor isincorporated within the matrix of the variable gauge stabilizer, withinthe matrix of a coating on the external surface 90, within a blade 91,or a recessed area 92. In a further embodiment, the corrosion inhibitoris incorporated within the pistons 93. In an embodiment, the variablegauge stabilizer includes seals (not shown) which are elastomeric andincorporate the corrosion inhibitor and/or nanostructure carrier.

FIG. 10 is an illustration of a centralizer 100 having elements inaccordance with an embodiment of the present invention. The centralizer100 has a plurality of fins 101, that may be bowsprings or othercentralizing means, and at least one collar 102 to attach to a downholeline 103. In an embodiment, the downhole line 103 is a wire or a tubularmember such as coiled tubing. In an embodiment, the corrosion inhibitoris incorporated within the plurality of fins 101, or the collar 102, orthe line 103, or combinations thereof. In an embodiment, the pluralityof fins 101, collar 102, or the line 103 include elastomers, and thecorrosion inhibitor and/or nanostructure carrier is incorporatedtherein.

FIG. 11 is an illustration of an agitator having elements in accordancewith an embodiment of the present invention. The agitator 110 has aninternal oscillating member 111, an oscillation passage 112, and seals(not shown). In an embodiment, the corrosion inhibitor is incorporatedwithin the matrix of the oscillating member 111, oscillation passage112, or the seals. In a further embodiment, the oscillating member 111,oscillation passage 112, or the seals include elastomeric elements andincorporate the corrosion inhibitor and/or nanostructure carrier.

FIG. 12 is an illustration of a packer having elements in accordancewith an embodiment of the invention. In an embodiment, the packer 120has a body 122, packing elements 124, and seating elements 126. In anembodiment, the packing elements 124 include an elastomeric compound. Inan embodiment, the packing elements 124 are axially compressed andthereby expand in a radial direction to form a seal against a casing orwellbore. In an embodiment, the packing elements are also hydraulicallyexpanded in a radial direction to form a seal against a casing orwellbore. In an embodiment, the corrosion inhibitor is contained withinthe packing elements 124 and is released in a controlled manner when thepacking elements 124 are compressed. In an embodiment, the seatingelements 126 contain a surface that seat or affix to a casing orwellbore when actuated. In an embodiment, the seating elements 126 areforced to expand in a radial direction to contact and engage against acasing or wellbore so that the packer 120 resists movement within thewell. In an embodiment, the corrosion inhibitor is incorporated withinthe matrix of the body 122, packing elements 124, seating elements 126,or other portions of the packer 120 whether shown or described herein ornot. In an embodiment, the corrosion inhibitor is incorporated within acoating of the body 122, packing elements 124, seating elements 126, orother portions of the packer 120.

FIG. 13 is an illustration of a fishing tool having elements inaccordance with an embodiment of the invention. The fishing tool 130 hasa spiral grapple 131, a guide 132, a spiral grapple control 133, apacker 134, and a bowl 135. In an embodiment, the corrosion inhibitor isincorporated within the matrix of the spiral grapple 131, the guide 132,the spiral grapple control 133, or the bowl 135. In an embodiment, thecorrosion inhibitor is released as these components wear. In anembodiment, the packer 134 is an elastomer and incorporates thecorrosion inhibitor and/or nanostructure carrier. FIG. 13 is anon-limiting example of a fishing tool. Numerous other types of fishingtools may incorporate the corrosion inhibitor with the matrix of thecomponents.

FIG. 14 is an illustration of a component of a blow out preventer havingelements in accordance with an embodiment of the present invention. Theblow out preventer has a ram shaft 140, a ram piston 142, a lockingpiston 144, an interior surface 146, at least one seal 148, and anexterior surface 150. In an embodiment, the corrosion inhibitor isincorporated within the matrix of the blow out preventer and iscontained within the matrix of a coating on a portion of the exteriorsurface 150. In an embodiment, the corrosion inhibitor is incorporatedin a lubricant for lubricating the ram shaft 140, ram piston 142, orlocking piston 144. In an embodiment, the corrosion inhibitor isincorporated in a hydraulic fluid (not shown) for actuating the ramshaft 140, ram piston 142, or locking piston 144. In an embodiment, thecorrosion inhibitor and/or nanostructure carrier is incorporated withinan elastomeric seal 148 or within the matrix of the interior surface146. FIG. 15 illustrates a fully assembled blow out preventer 152. In anembodiment, the corrosion inhibitor is incorporated with the matrix of acoating on a portion of the external surface of the blow out preventer150 that may encounter a corrosive environment.

In embodiments, the corrosion inhibitor are incorporated within thematrix of any component of the drill string or downhole assemblyincluding lift rods, lift pumps, coiled tubing, drill pipe, or casingthat may encounter a corrosive environment. In furthermore embodiments,the corrosion inhibitor is incorporated within the matrix of a coatingon any component of the drill string including a drill bit, a rotor, astator, a motor, a pump, a drive shaft assembly, a dump sub, a bearingassembly, a blowout preventer (BOP), a packer, drill pipe, tubing,casing, a completion tool, a production tool, a fishing tool, anagitator, a stabilizer, a centralizer, and combinations thereof that mayencounter a corrosive environment

Various terms are used herein, to the extent a term used in not definedherein, it should be given the broadest definition persons in thepertinent art have given that term as reflected in printed publicationsand issued patents.

As used herein, the term “attaching” means combining two or morematerials in any manner, such as absorbing, activating, affixing,bonding, filling, impregnating, and the like, or combinations thereof.

As used herein, the term “adjacent” means locating proximately andincludes adjoining, abutting, encasing, mixing, embedding, and the like,or combinations thereof.

As used herein the term “nanostructure” refers to a material having atleast one dimension of less than 100 nm.

As used herein, the term “polymeric component” refers to the polymerphase of a nanocomposite.

As used herein, the term “carrier” refers to a medium for supplying acorrosion inhibitor.

As used herein, the term “corrosion inhibitor” includes a chemicalcompound that decreases the corrosion rate of a metal or an alloy.

Depending on the context, all references herein to the “invention” mayin some cases refer to certain specific embodiments only. In other casesit may refer to subject matter recited in one or more, but notnecessarily all, of the claims. While the foregoing is directed toembodiments, versions and examples of the present invention, which areincluded to enable a person of ordinary skill in the art to make and usethe inventions when the information in this patent is combined withavailable information and technology, the inventions are not limited toonly these particular embodiments, versions and examples. Other andfurther embodiments, versions and examples of the invention may bedevised without departing from the basic scope thereof.

1. A method of supplying a corrosion inhibitor to a downhole metalcomponent, comprising: forming a nanostructure carrier configured as aninsert on a downhole tool; impregnating the nanostructure carrier with acorrosion inhibitor; positioning the nanostructure carrier in anenvironment adjacent a downhole component; and releasing the corrosioninhibitor from the nanostructure carrier into the environment adjacentthe downhole metal component.
 2. The method of claim 1, wherein forminga carrier comprises forming a material having a nanoporosity consistingof at least one material chosen from the group consisting of:kaolinites, halloysites, chrysotiles, montmorillonites, hectorites,beidellites, saponites, muscovites, phlogopites, talcs, pyrophyllites,vermiculites, chlorites, carbon black, carbon nanotubes, carbonnanobuds, carbon nanohorns, fullerenes, polyamides, polyacetals,polycarbonates, polyoxytetramethyleneoxyterephthaloyl,polybutyleneterephthalate, polyethyleneterephthalate, polyimide,polyphenylenesulfide, polysulfones, polyarylates, epoxies, polyphenyleneether resins, metal oxyhydroxides, and combinations thereof.
 3. Themethod of claim 1, wherein a corrosion inhibitor comprises at least onecomposition chosen from the group consisting of carbonates, silicates,phosphates, chromates, cerates, molybdates, vanadates, organic moleculescontaining heteroatoms such as nitrogen, sulfur, phosphorus and oxygen,anthranilic acid, thiols, organic phosphonates, organic carboxylates,organic anions, organic cations, and combinations thereof.
 4. The methodof claim 1, wherein releasing the corrosion inhibitor comprises exposingthe carrier to at least one mechanical condition chosen from the groupconsisting of impact, surface agitation, abrasion, shear, an alterationin the carrier structure, and combinations thereof.
 5. The method ofclaim 1, wherein releasing the corrosion inhibitor from the carrierfurther comprises causing the corrosion inhibitor to be released uponthe occurrence of at least one change in the conditions in theenvironment adjacent the downhole component chosen from the groupconsisting of pressure changes, temperature changes, pH changes,chemical changes, and combinations thereof.
 6. The method of claim 1,wherein releasing the corrosion inhibitor from the carrier into theenvironment adjacent the downhole component comprises controlling therelease of the corrosion inhibitor.
 7. The method of claim 6, whereincontrolling the corrosion inhibitor release comprises an on-demandrelease by workers in the field.
 8. A method of supplying the corrosioninhibitor to a downhole metal component, comprising: forming ananostructure elastomer, configured for placement within a downholetool; impregnating the nanostructure elastomer with a corrosioninhibitor; positioning the nanostructure elastomer in an environmentadjacent a downhole component; and releasing the corrosion inhibitorfrom the nanostructure elastomer into the environment adjacent thedownhole metal component.
 9. The method of claim 8, wherein forming anelastomer further comprises forming an elastomer having a nanostructurewith nanoporosity.
 10. The method of claim 8, wherein impregnating theelastomer with a corrosion inhibitor comprises impregnating theelastomer with a corrosion inhibitor that is attached to a nanostructurecarrier.
 11. The method of claim 8, wherein configuring the elastomerfurther comprises configuring the elastomer to release the corrosioninhibitor into the environment adjacent the downhole component inresponse to a condition chosen from the group consisting of impact,surface agitation, abrasion, shear, pressure changes, temperaturechanges, pH changes, chemical changes, and combinations thereof.
 12. Themethod of claim 11, wherein configuring the elastomer to release thecorrosion inhibitor into the environment adjacent the downhole comprisescontrolling the release of the corrosion inhibitor.
 13. The method ofclaim 12 wherein controlling the elastomer release of the corrosion intothe environment adjacent the downhole comprises on-demand release byworkers in the field.